The trace here should be taken using \({\rm tr}\left(\hat{P}_{\bf p^{\prime }}^{(\pm )}\hat{P}_{\bf p}^{(\pm )}\right) =[1+({\bf p}\cdot {\bf p^{\prime }})/pp^{\prime }]/2\)  and \({\rm tr}\left(\hat{P}_{\bf p^{\prime }}^{(\pm )}\hat{P}_{\bf p}^{(\mp )}\right)=[1-({\bf p}\cdot {\bf p^{\prime }})/pp^{\prime }]/2\) . This result differs from the standard
consideration, [1]} because interference of electron and hole states gives an essential contribution to \(W(\varepsilon ,\varepsilon ^{\prime })\) 
due to the matrix structure of the spectral density functions. After the integrations over \(\bf p\) -plane, one transforms (11) into
\(W(\varepsilon ,\varepsilon ^{\prime })\equiv \Theta _{GR}w(\varepsilon /T,-\varepsilon ^{\prime }/T) /T^2 , \\\Theta _{GR}=\frac{\upsilon _{ac}s}{\upsilon ^2}\frac{T}{\hbar }\left(\frac{T}{\pi \hbar \upsilon }\right)^2 , ~~~~~~ \upsilon _{ac}=\frac{D^2T}{4\hbar ^2\rho _s\upsilon s^2} , \nonumber \) 
